The world is not big enough

If much of the green movement is in denial about the threat posed by population growth, it is not hard to see why. George Monbiot (Comment, January 29) repeats a strangely pervasive error when he says that "total population growth in England is responsible for only about 35% of the demand for homes". In fact, the household projections published last March demonstrate that population growth is the biggest factor in housing growth, accounting, according to government figures, for 59% of the 223,000 additional households projected each year up to 2026. Changing age distribution accounts for 20%, while smaller households account for a mere 17%.

The myth that household size is to blame is much beloved of environmental groups who campaign against the loss of green space but rarely mention population growth. I fear that George's article, though in many respects sensible, will confirm the notion that population increase is somehow a second-order cause of environmental crisis.

On the basis of the latest population and household size projections, the Optimum Population Trust estimates that by 2081 the UK will require over 40m homes - 15m more than we have now. No amount of vegetarianism or economic frugality will change that. Valerie Stevens Chair, Optimum Population Trust

We welcome the fact that George Monbiot has at last tackled the issue of population growth. He is right to draw attention to the damage done by the rich "minority" world. That is why the Population and Sustainability Network addresses both sides of the coin - population growth and consumption, with particular reference to climate change.

A parliamentary report concluded that none of the millennium development goals could be delivered without attention to population growth. Let us have an honest debate about population in order that it may receive the urgent attention it deserves.Catherine Budgett-Meakin Population and Sustainability Network

It is refreshing to see an environmental journalist help bring the issue of population back to the mainstream of environmental debate. Most refreshing of all is that he has looked at all the straws that other environmentalists grasp at and found they are just that, straws. Of course, increased consumerism, smaller households and more meat-eating are all important factors, but none of these make population growth less important. But, having grasped the necessity for halting population growth, why does it have to be presented as if that was all it is, a necessity. We should see it as an opportunity in which the whole world will be the winners. Christopher Padley Market Rasen, Lincolnshire

It was refreshing to read Simon Fairlie's article (A load of hot air?, Society, January 30) exploring the complexity of assessing the impact of farming on the environment. The vegan lobby has for too long presented an oversimplified version.

The charity Send a Cow has been implementing small-scale farming projects in Africa for 20 years. Initial findings indicate that our programmes are, in fact, carbon positive. Farmers plant fodder trees and enrich their soil with manure, absorbing far more carbon than is emitted by the cows.

Certainly, more research is needed if the world's population is to feed itself without harming the environment. But we must not forget that farm animals offer good nutrition, free fertiliser and income potential to poor families. Those families must be regarded as victims, not perpetrators, of climate change. Martin Geake Chief executive, Send a Cow

Claiming that climate change due to meat production is "a load of hot air" is irresponsible. While the UN report states that "raising animals for food generates more greenhouse gases than all the cars in the world combined", it's not the only reason for alarm. A Japanese study found that 1kg of beef emits as much greenhouse gas as driving a car for 155 miles. The only sane solution is to go vegetarian. Alexia WeeksPeople for the Ethical Treatment of Animals

· This article was amended on Tuesday February 5 2008. One of the above letters was from Catherine Budgett-Meakin who works at the Population and Sustainability Network, not the Population and Stability Network as we said. This has been corrected.